A foreign scientist named Petrov has offered to sell his Portable Power Paralyzer, a compact device that can immobilize any machine, to the U.S. Government's Bureau of Secret Projects for $30,000. On board a non-stop train to Washington DC the BSP agent trailing Petrov is killed, so Bureau Chief Barton J. Reed calls a Purple Alert summoning service station owner Stanley Beamish to take the power pill that turns him into Mr. Terrific. Stanley uses his terrific powers to board the train and unknowingly receives the device when Petrov switches matchbooks with him. Stanley then mistakes a toy salesman for his contact and pays 30 grand for a simple child's doll. The matches change hands a few times before Stanley's partner Hal winds up with them and is subsequently captured by a beautiful foreign agent named Mala. Stanley uses his back up ""booster"" pills to catch up with the bad guys, rescue Hal and recover the Paralyzer.

Mr. Terrific is put on the trail of a mysterious crime boss, but attempts to reach ""Mr. Big"" lead to several dunkings for Stanley who keeps misplacing his booster pills. Mr. Big turns out to be a woman, but our hero doesn't have to manhandle the lady. The dunkings have given him a cold and created a new weapon in Mr. Terrific's arsenal: the super sneeze.

Mr. Terrific's power pills fail him just when a crippled airplane sends out an SOS. The plane is in for a big letdown unless the Government men can get Mr. Terrific airborne.

Stanley's suspicious behavior, as he tries to solve a jewel robbery, leads Hal to believe that his best friend has become a crook.

Spies who have stolen the formula for the power pill trail B.J. Reed and determine that Mr. Terrific works at Hal and Stanley's Service Station as a front. They plan to kidnap our hero and either lure him to their side or brainwash him. The shapely Nina (Joan Huntington) at first charms and hypnotizes Hal. When the pills don't work on him, she returns for Stanley. Although the enemy agents learn that Stanley is on to them, he still manages to swallow some of the pills they have produced and captures the gang of villains.

Safe cracker ""Fingers"" Maclaine (Stephen Strimpell in a dual role) is released from prison two days early. Anxious to see his girl Dolly and to meet the new criminal gang he's joining, Fingers soon finds himself again in police custody and finishing his sentence in a small hotel room. B.J. Reed has arranged for Stanley Beamish, armed with a supply of power pills, to infiltrate the gang of bank robbers while his double Fingers sits twiddling his thumbs. The real Fingers escapes and uses his underworld connections to find out what's going on. When he appears at the gang's hideout, the jig is up for Stanley. Our hero must use his wits, such as they are, to trick the crooks into letting him take a power pill so that he can turn the tables and send them all up the river.

Stanley must go the distance with a professional caliber boxer in order to break up a crime syndicate that's working out of a gymnasium. There's just one problem: the fight's about to start and Stanley's power pill is nowhere to be found.

Stanley goes undercover as a prison inmate so that he can attempt to ferret out the location of a criminal's hidden loot.

A defecting Soviet ballerina needs Stanley's help to get away from her countrymen. Stanley needs help retrieving his lost booster pill.

B.J. calls a Purple Alert, when escaped murderer Herman J. Von Brock wants to kill Harley for helping to send him to prison. Stanley moves into Harley's home as a 24-hour guard, but a threatening note tossed from a speeding car sends the agents to Hal and Stanley's apartment. A bored Harley volunteers to do some work at the service station, where he is grabbed by the killer. Stanley and B.J. spot Von Brock's car from the air, but Stanley's power goes off. This time it's Barton J. Reed to the rescue as he tackles Von Brock and sits on the killer's chest until help arrives. Seldom has justice been meted out so cruelly on a 1960s sitcom.

In hill country, Stanley must find an illegal still and stop a shotgun wedding.

Stanley is asked to demonstrate his powers for several representatives of foreign nations. One of them is an impostor who wants to kidnap Mr. Terrific.

A dentist who's been using truth gas to get secrets from government agents changes tactics and places a tiny transmitter in Stanley's tooth.

Stanley laces up his sneaks, and turns on the terrific speed, when he's assigned to locate a kidnapped athlete.

Our hero accidentally gives a genuine set of vital blueprints to an enemy agent and keeps the phonies for our side.

The search for a stolen code book sends Stanley undercover and under the big top. Ultimately he has to power up and battle several performers and a gorilla in order to accomplish his mission.

The Bureau of Secret Projects must protect a visiting Sultan, so Stanley powers up and becomes a sort of Turbanator.